A recent Google webmasters video brings out an interesting question:
Should a webmaster make the internal links “nofollow” within their site, or it doesn’t make any difference as they are only internal links?
Let us first understand the working of Nofollow links:
It is an HTML value that prevents a link to send any “link juice” to the page where that nofollow link is directed. It only allows a website to post links without giving any PageRank to the page associated with the link.
Based on this, the question asked to Matt Cutts is:
Does it make sense to nofollow the internal links, for e.g. the login page of my website?
Giving the same definition of nofollow links as given above in this post, Matt Cutts has to say that he would try to leave the nofollow off.
He further added that if there is a link to a page from one page on your site and you would want the spiders to locate that page. So, for every internal links in your website, that is a link from one page to another page on your site would definitely get a PageRank flow. This clearly means that you could leave the nofollow attribute alone.
Although, it doesn’t hurt Google at all to crawl all the pages, there could be some exceptions while applying this rule. For example, one could put the nofollow for a link pointing to a login page or also some pages like the terms and conditions page or other “useless pages”, which are not meant to help the conversion or any other goals. Even if there isn’t any nofollow for these links, Google won’t mind it.
Cutts brought up the fact that nofollow is a helpful tool when you are planning to link to external sites. He stresses that forum profile links and blog comments links are something that should be nofollowed. While giving an authentic link, make sure that it is the site that you can put your faith upon and is high authority site.
He also suggests that if there are pages on your website which you would not like to be followed, you could also use no index, in order to avoid their indexing by Google. Also he made one valid statement that many a times having the login pages indexed is quite good for users so that they could simply find the login page and log in to you site.
Cutts also gave an important reminder: It makes sense to ensure that Googlebots are able to crawl the internal pages of your site.